Descripción:Boeing 727-22C N7434U operated Flight 266 from Los Angeles to Denver, CO and Milwaukee, WI. The aircraft had been operating since January 15, 1969, with the No. 3 generator inoperative. This was allowed because according to the Minimum Equipment List, the aircraft is airworthy with only two generators operable provided certain procedures are followed and electrical loads are monitored during flight.Flight 266 was scheduled to depart the gate at 17:55, but was delayed until 18:07 because of the inclement weather and loading problems. The flight commenced its takeoff roll on runway 24 at approximately 18:17. At 18:18:30 the sound of an engine fire warning bell was heard in the cockpit. The crew reported a no. 1 engine fire warning and stated that they wanted to return to the airport. Shortly after shutdown of the No. 1 engine, electrical power from the remaining generator (No. 2) was lost. Following loss of all generator power, the standby electrical system either was not activated or failed to function. Electrical power at a voltage level of approximately 50 volts was restored approximately a minute and a half after loss ofthe No. 2 generator. The duration of this power restoration was just 9 to 15 seconds. The Boeing descended and struck the sea 11.3 miles west of the airport. The ocean depth at this point is approximately 950 feet.

PROBABLE CAUSE: "The loss of attitude orientation during a night, instrument departure in which all attitude instruments were disabled by loss of electrical power. The Board has been unable to determine (a) why all generator power was lost or (b) why the standby electrical power system either was not activated or failed to function."

Requiring B727 operators to provide a means to prevent inadvertent operation of the battery switch in those aircraft in which the battery switch is located within 10 inches of the galley power switch.

Issued: 02-JUL-1969

To:

A-69-017

BY LETTER DATED JULY 11, 1969, THE CHAIRMAN OF THE SAFETY BOARD RECOMMENDED TO THE ADMINISTRATOR OF THE FAA THAT THE AUTOMATIC SWITCHING OF ESSENTIAL POWER TO STANDBY POWER UPON LOSS OF ALL GENERATORS BE MADE A MANDATORY REQUIREMENT FOR ALL TURBINE-POWERED AIRCRAFT. IT WAS FURTHER RECOMMENDED THAT UNTIL SUCH TIME AS THE ABOVE REQUIREMENT COULD BE IMPLEMENTED THROUGHOUT THE INDUSTRY, THE EMERGENCY CHECKLISTS FOR ALL AIRLINES PERTAINING TO "LOSS OF ALL GENERATORS" REQUIRE THAT THE SECOND OFFICER, OR CAPTAIN IF APPROPRIATE, CHECK TO ASSURE THAT THE BATTERY SWITCH IS ON, THEN IMMEDIATELY SWITCH ESSENTIAL POWER TO THE STANDBY OR EMERGENCY POSITION. IT WAS THE SAFETY BOARD\'S VIEW THAT THIS WOULD GIVE THE CAPTAIN THE INSTRUMENTS AND LIGHTS NECESSARY TO FLY THE AIRCRAFT WHILE THE SECOND OFFICER COULD "TROUBLESHOOT" THE ELECTRICAL SYSTEM. (Closed - Acceptable Action)

Issued: 01-AUG-1969

To: Boeing 727

AD 69-25-01

Requiring the installation of a capacitor for the purpose of filtering out electrical interference which may be present to a sufficient extent on some B727 aircraft that, under an overloaded condition, the generator control panel may disable the generator before opening the bus tie circuit breaker.

Issued: 10-SEP-1969

To: Boeing 727

AD 69…

Required replacement of two silicon controlled switches with a transistorized amplifier and a miniature two-pole relay on B727 airplanes. As a reason for this replacement, the FAA cited failures of the generator overload protection circuit silicon controlled rectifiers, causing a single generator system lockout on B727 aircraft.

Issued: 12-SEP-1969

To: Boeing 727, 727C, and 727-200

AD 69-16-01

Requiring revision of the Boeing 727 Airplane Flight Manual to provide the flight crew with more complete procedures to be followed if all generators are lost.

Issued: 18-MAR-1970

To:

A-70-018

THE BOARD RECOMMENDED THAT THE SECOND OFFICER ON A B-727 BE PROVIDED WITH A POSITIVE INDICATION ON HIS PANEL WHEN THE STANDBY SYSTEM IS BEING POWERED FROM THE BATTERY. SUCH AN INDICATION COULD TAKE THE FORM OF A LIGHT, SUCH AS THAT INSTALLED ON THE B-747 AIRCRAFT FOR THE SAME PURPOSE. THE LIGHT WOULD BECOME ILLUMINATED WHEN THE STANDBY SYSTEM IS ACTIVATED. ANOTHER ALTERATION WHICH MIGHT BE CONSIDERED IN CONNECTION WITH THE FOREGOING RECOMMENDATION WOULD BE THE TRANSFER OF THE STANDBY FEATURE FROM THE ESSENTIAL POWER SELECTOR SWITCH TO A SEPARATE ON-OFF TOGGLE SWITCH, WHICH AGAIN IS THE ARRANGEMENT ON THE B-747. THE ADDITION OF SUCH A SWITCH WOULD NOT ONLY SERVE TO SIMPLIFY ACTIVATION OF THE STANDBY SYSTEM, BUT WOULD ALSO FACILITATE TROUBLESHOOTING THE GENERATORS WHEN THE STANDBY SYSTEM IS ON. (Closed - Acceptable Action)

This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path. Distance from Los Angeles International Airport, CA to Denver-Stapleton International Airport, CO as the crow flies is 1356 km (848 miles).